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Intervals, chords and progressions

Hear single elements first, then how they build music.

Intervals have a number and a quality

An interval's number counts the letter names, including both ends; its quality also depends on the number of semitones. C–E is a major third (4 semitones), C–E♭ a minor third (3); C–F is a perfect fourth (5) and C–G a perfect fifth (7). The same number of semitones can be spelled differently, such as an augmented fourth and a diminished fifth.

The four basic triads

Counting semitones from the root: major 0, 4, 7; minor 0, 3, 7; diminished 0, 3, 6; augmented 0, 4, 8. A chord's quality and its root's pitch are separate things; an inversion changes the bass but not necessarily the root or quality.

The diatonic triads of C major

In order: C, Dm, Em, F, G, Am, Bdim — I, ii, iii, IV, V, vi, vii°. Roman numerals give a chord's root position in the key, with upper/lower case usually meaning major/minor quality; degree numbers describe single notes. Don't mix them up.

Hear progressions, don't memorise sounds

Find the tonic and the bass line first, then work out each chord's quality and position in the key. I–IV–V–I is often used to establish a key — a common training context, not the only rule in music. The Chord qualities, Diatonic chords and Chord progressions exercises here each train something different.

References: Functional Ear Trainer · Miles.be · Puget Sound · Music Theory for the 21st-Century Classroom · musictheory.net · Lessons